Scaling effects of relaxor-PbTiO(3) crystals and composites for high frequency ultrasound.

The dielectric and piezoelectric properties of Pb(Mg(13)Nb(23))O(3)-PbTiO(3) (PMN-PT) and Pb(In(12)Nb(12))O(3)-Pb(Mg(13)Nb(23))O(3)-PbTiO(3) (PIN-PMN-PT) ferroelectric single crystals were investigated as a function of thicknessscale in monolithic and piezoelectricpolymer 1-3 composites. For the case of PMN-PT single crystals, the dielectric (epsilon33Tepsilon0) and electromechanical properties (k(33)) were found to significantly decrease with decreasing thickness (500-40 mum), while minimal thickness dependency was observed for PIN-PMN-PT single crystals. Temperature dependent dielectric behavior of the crystals suggested that the observed thickness dependence in PMN-PT was strongly related to their relatively large domain size (>10-20 mum). As anticipated, 1-3 composite comprised of PIN-PMN-PT crystals exhibited superior properties to that of PMN-PT composite at high frequencies (>20 MHz). However, the observed couplings, being on the order of 80%, were disappointedly low when compared to their monolithic counterparts, the result of surface damage introduced during the dicing process, as evidenced by the broadened [002] peaks in the x-ray diffraction pattern.